// var可以重复声明变量
console.log(age) //undefined
var age = 10
var age = 20
console.log(age)//20

// let不能重复声明变量

// console.log(name) //name is not defined 不存在预解析，变量提升，提前调用报未定义错误
let name = 'li'
name = 'zs'
console.log(name) //zs
let arr=[1,2,3]
arr=[4,5,6]
console.log(arr) //[ 4, 5, 6 ]

